Every auto paint I have shot has used a hardener. Every auto paint I have used is fuel proof to the 30% fuel I have used. You can also get a clear coat that matches the paint you have and use a dull coat to make it FLAT. I have added the dulling agent to make it military flat. There was no shine at all. The store I deal with has put a two part clear in a spray can for me. It was $15.00 for the can but well worth it.

With the paint I used and the HVLP gun I had, I had to increase the reducer by about 30% to keep it from giving me an orange peel. You may have to play with the paint a little.

Dru.